GABA

Unproven· human data

Also known as: Gamma-aminobutyric acid

The brain's calming neurotransmitter, but oral doses barely reach the brain.

GABA is the brain's main inhibitory (calming) neurotransmitter, which makes an oral 'GABA' supplement sound appealing for relaxation and sleep.

The core problem is that ingested GABA crosses the blood–brain barrier poorly, so it is unclear how much reaches the brain. Some studies report modest relaxation or stress effects, possibly via the gut or a placebo response, but the evidence is weak and the mechanism doubtful.

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Written and reviewed by Mathew Beale, MSc Biotechnology, University of Reading.

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